CPU Comparison
Intel Core i7-5650U
Core i7-975
PERFORMANCE BENCHMARKS
Analysis: Intel Core i7-5650U vs Intel Core i7-975
Head-to-Head Benchmarks
The benchmark data presents a remarkably consistent picture: the Intel Core i7-975 wins every single head-to-head comparison, with the i7-5650U trailing by nearly identical margins across all five tests. In Cinebench R15 multicore, the i7-975 scores 299 against the i7-5650U's 256, a delta of -14.4%. The pattern repeats in Cinebench R20 multicore (1249 vs 1067, -14.6%) and Cinebench R23 multicore (2974 vs 2542, -14.5%). Even in single-core workloads, where the newer Broadwell architecture might be expected to narrow the gap, the i7-975 leads by 14.3% in R20 single-core (175 vs 150) and 14.6% in R23 single-core (419 vs 358).
The consistency of these deltas, all clustering between -14.3% and -14.6%, suggests the performance difference is systemic rather than workload-specific. The i7-975's advantage stems from its physical configuration: 4 cores and 8 threads against the i7-5650U's 2 cores and 4 threads. This is not a case of architectural efficiency overcoming core-count disparity; the older Nehalem design simply has more execution resources to bring to bear.
In the broader context, both processors sit at the 28th percentile among all CPUs, indicating they occupy similar tiers in the overall performance landscape despite their head-to-head differences. The i7-5650U's average benchmark score of 1027 places it in a dead heat with the AMD Ryzen Embedded V1202B (1027, 0% delta) and just ahead of the Intel Core i3-4340 (1026, 0.1%) and Intel Processor N150 (1025, 0.2%). The i7-975's average score of 1023 puts it virtually even with the AMD Ryzen 5 PRO 2500U (1024, 0%) and AMD Phenom II X6 1075T (1024, -0.1%), while trailing the Intel Processor N150 by a hair (1025, -0.2%).
Where Each One Wins
The i7-975 wins in every measured benchmark category. In multicore workloads, the advantage is straightforward: its 4 cores and 8 threads allow it to process parallel tasks more effectively. The Cinebench R23 multicore result of 2974 versus 2542 represents a 14.5% advantage that will manifest in rendering, video encoding, and other heavily threaded applications.
What is more telling is the single-core performance. The i7-5650U runs at a base clock of 2.20 GHz with a boost of 3.20 GHz, while the i7-975 operates at 3.33 GHz base and 3.60 GHz boost. Despite the i7-5650U's newer 14 nm Broadwell architecture versus the i7-975's 45 nm Nehalem design, the raw clock speed advantage of the i7-975 (0.4 GHz higher boost) translates directly into single-thread wins. The R23 single-core scores (419 vs 358) show a 14.6% gap that cannot be explained by architecture alone, clock speed remains the dominant factor.
The i7-5650U's only "wins" are qualitative. It integrates Intel HD 6000 graphics, while the i7-975 has no integrated graphics at all. The i7-5650U also draws dramatically less power (15 W TDP vs 130 W TDP), making it suitable for mobile platforms. However, in pure computational benchmarks, there is no category where the i7-5650U comes out ahead.
Architecture Differences
The two processors represent opposite ends of Intel's design philosophy. The i7-5650U is a Broadwell-U mobile part built on a 14 nm process with 1,900 million transistors packed into a 133 mm² die. The i7-975 is a Nehalem-era Bloomfield desktop part manufactured on 45 nm with 731 million transistors on a much larger 263 mm² die. The transistor density difference is stark, the newer process packs more than 2.5 times the transistors into roughly half the die area.
Cache configurations also differ meaningfully. Both share 64 KB L1 and 256 KB L2 per core, but the i7-975 doubles the shared L3 cache to 8 MB versus the i7-5650U's 4 MB. This larger last-level cache likely contributes to the i7-975's consistent lead, particularly in workloads with moderate working sets.
Memory subsystems diverge as well. The i7-5650U supports dual-channel DDR3 with a theoretical bandwidth of 29.9 GB/s, while the i7-975 uses triple-channel DDR3 at 25.6 GB/s. Interestingly, the newer mobile chip has higher peak memory bandwidth, yet this does not translate into benchmark wins, suggesting that raw memory bandwidth is not the limiting factor in these tests.
The i7-975 features an unlocked multiplier, enabling overclocking, while the i7-5650U is locked. The i7-975 uses Intel Socket 1366, the i7-5650U uses Intel BGA 1168 (soldered, not upgradeable). PCIe support also differs: the i7-5650U provides Gen 2 with 12 lanes (CPU only), while the i7-975 lists Gen 2 without a specific lane count. Neither supports ECC memory. The i7-975 launched on 2009-06-01 with an MSRP of $1059; the i7-5650U launched on 2015-02-28 with an MSRP of $426. Both are end-of-life products.
The Verdict
The data is unambiguous: the Intel Core i7-975 is the faster processor in every measured benchmark. Its 4-core/8-thread configuration, higher clock speeds (3.33 GHz base, 3.60 GHz boost), and 8 MB L3 cache give it a consistent 14.3-14.6% advantage across all Cinebench tests, both single-core and multicore. For any workload that stresses CPU compute, rendering, compilation, scientific computing, the i7-975 is the superior choice.
However, the i7-5650U is not without rationale for selection. It consumes 15 W versus 130 W, a difference of 115 W that makes it viable in ultraportable laptops where the i7-975's desktop platform with Socket 1366 would be impossible. The i7-5650U also includes integrated Intel HD 6000 graphics, eliminating the need for a discrete GPU in basic systems. Its launch MSRP of $426 is substantially lower than the i7-975's $1059, though both are now end-of-life products.
Users who need raw compute performance and have the power budget and physical space for a desktop platform should choose the i7-975. Users who require a mobile, low-power solution with integrated graphics and are willing to accept a 14.5% performance deficit should choose the i7-5650U. There is no scenario in the benchmark data where the i7-5650U outperforms the i7-975 in computational speed.
FAQ
Q: Which processor is faster in multi-core workloads?
A: The Intel Core i7-975 is consistently faster, winning Cinebench R15 multicore (299 vs 256, -14.4%), R20 multicore (1249 vs 1067, -14.6%), and R23 multicore (2974 vs 2542, -14.5%).
Q: Does the newer architecture of the i7-5650U help in single-core tests?
A: No. Despite the 14 nm Broadwell design versus the 45 nm Nehalem, the i7-975 still wins single-core tests by 14.3% in R20 (175 vs 150) and 14.6% in R23 (419 vs 358), driven by its higher clock speeds.
Q: How do these processors compare to other CPUs in the database?
A: Both sit at the 28th percentile among all CPUs. The i7-5650U averages 1027, matching the AMD Ryzen Embedded V1202B (1027, 0%) and edging the Intel Core i3-4340 (1026, 0.1%). The i7-975 averages 1023, nearly identical to the AMD Ryzen 5 PRO 2500U (1024, 0%).
Q: What are the core and thread counts for each?
A: The i7-5650U has 2 cores and 4 threads, while the i7-975 has 4 cores and 8 threads. The i7-975's doubled core count is the primary driver of its multicore advantage.
Q: Do both processors support the same memory configuration?
A: No. The i7-5650U uses dual-channel DDR3 with 29.9 GB/s bandwidth, while the i7-975 uses triple-channel DDR3 with 25.6 GB/s. The i7-5650U has higher peak bandwidth despite being slower in benchmarks.
Q: Which processor has integrated graphics?
A: Only the i7-5650U includes integrated graphics (Intel HD 6000). The i7-975 has no integrated graphics, requiring a discrete GPU for display output.